My pediatrician said that group b + could be treated before you are in labor. Eliminating the need for IV anti during delivery.
Options for how it is 'treated' is a question to ask the OB.
I also learner that group b runs in cycles that are weeks long. So if you were negative at 37 weeks you would most likely remain negative through labor.
Either way with or without antibiotics and positive or negative, be aware of the signs and monitor your tiny ones.